It would be great, if your application could create interaction flow maps for user's projects. Firstly, it is very useful, when designing communicates with developers. Secondly, it is helpful, because when you create the prototype, you can see where (on which page) you can create something more convenient. Moreover, if you watch at the map, you would see all your mistakes.
So, I think, the map is indispensable thing during a prototyping. And I will look forward to this update.

For now when you create an android mock there is no way to set tablet size like 1280x800. You can set working area size, but preview will show phone (with initial phone size) anyway.
iPad mock has only iOS specific items

It should be possible to add the assets from outside (upload) from users exisitng element libraries, and not only create them in the app as described, for many it could save time building the own asset library:)

I don't know if it's a specific problem I'm having, or if this really is not possible as of now, but, when I added an item to a menu, I couldn't align the text to the left - it was stuck to the center. I think that would be a necessary feature, if it does not exist already.